Problem: My smart sensor data shows a -888.888 for a good portion of the data file.

Note: -888.888 means that the logger could not find the smart sensor after the logger was launched successfully.

Likely reasons:

  • Sensor is unplugged
  • Corrosion due to water damage in smart sensor housing
  • Corrosion on RJ 12 connector in logger
  • Cut obus cord (wire connected from logger to smart sensor housing)
  • Direct or nearby lightning strike


  • Relaunch solution:
    • Most of the time you can relaunch the logger and this error will clear. (There is nothing you can do about past data.)
  • Corrosion solution:
    • Clean off corrosion and let dry.
    • Use drip loop in the installation so water will not wick into smart sensor.
  • Cut wire solution:
    • Reattach wires matching the wire colors.
    • Seal connections and relaunch.
  • Lightning Strike:
    • Make sure logger is grounded properly. We provide a 4-ft grounding rod but this might not be enough. Electrical code now requires 2 x 8 ft rods placed 6 feet apart.

If you need to repair a cable, use the attached files to help.

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Tech Note
Troubleshooting & Maintenance